The present invention relates to a transmission composed of a motor, a differential mechanism and a power coupling mechanism, as well as a vehicle using the same.
As a drive system capable of attaining a low power consumption of an engine there is known a hybrid vehicle which utilizes a driving force of a motor.
As to the hybrid vehicle, there has been proposed a system which uses two motors and one planetary gear. For example, in Japanese Patent Laid Open No. Hei 7-135701 there is described a method in which a control is made by a generator so that a driving force of an engine is inputted to a planetary gear and so that the vehicle is driven by a driving force obtained from an output shaft of the planetary gear.
In the above method, out of three constituent gears of the planetary gear, other gears than a gear connected to a shaft of the engine are controlled on their speed so as to stop the gear connected to the engine shaft, thereby realizing a vehicular running with a motor alone.
In high-speed running, a shaft of the generator is fixed electrically and the driving force of the engine is transmitted to a vehicle driving shaft through the other gears in the planetary gear than the gear connected to the engine shaft.
In the above method, however, there occurs a loss due to follow-up rotation of the generator during vehicular running with the motor, resulting in consumption of the driving motor output.
In high-speed running, moreover, an electric energy for stopping the rotation of the generator is consumed.
Further, torque assist by the generator is restricted due to a constraint based on the planetary gear.